The 23-year-old's future remains in limbo as both the Blades and United discuss where Henderson will be next season.
Moore said: "Yes he definitely is. Last year in the Championship he was the best goalkeeper, and he's carried that on this season in the Premier League.
"The big thing with Deano is that he backs up what he says. He has a clear goal in his head, to be England's No 1.
“I think he's well on the way to doing that. He's an exceptional talent.
"This season in the Premier League has done him the world of good to stake his claim as England's No 1.
"It's difficult being behind him with game time limited, but at the same time I'm delighted for Deano because he's a great lad and since he joined he's captured the fans' hearts.
"His performances back up what he says off the pitch. That's what I like about Deano. If he says he's going to do something, he will do it.
“He's going to have a great career and I genuinely believe he will be England's No 1 at one point."